On the invariants of velocity and magnetic field gradient tensors in MHD theory

2020 ◽  
Author(s):  
Giuseppe Consolini ◽  
Virgilio Quattrociocchi ◽  
Massimo Materassi ◽  
Tommaso Alberti ◽  
Mirko Stumpo
Keyword(s):  
Magnetic Field ◽  
Field Gradient ◽  
Magnetic Field Gradient ◽  
Point Of View ◽  
Space Plasmas ◽  
Lagrangian Point ◽  
Statistical Features ◽  
Mhd Turbulence ◽  
Gradient Tensor ◽  
Topological Features

<p>In the framework of MHD turbulence, the velocity and magnetic field topological features can be characterized by three quantities invariant under rotations, which are defined by the velocity and magnetic field gradient tensors. These quantities provide information about field structures and dissipative features. <br>In this work we present a preliminary derivation of the evolution of the invariant quantities of the velocity and magnetic field gradient tensors in the framework of MHD theory, using a Lagrangian point of view. This work can be considered as a first step useful to characterize and describe the evolution of the fields structures in  heliospheric space plasmas. Furthermore, some examples of the statistical features of magnetic field gradient tensor invariants, in the inertial and dissipation ranges, are also shown and discussed. </p>

On Geometrical Invariants of the Magnetic Field Gradient Tensor in Turbulent Space Plasmas: Scale Variability in the Inertial Range

2019 ◽  
Vol 878 (2) ◽  
pp. 124 ◽  
Author(s):  
Virgilio Quattrociocchi ◽  
Giuseppe Consolini ◽  
Maria Federica Marcucci ◽  
Massimo Materassi
Keyword(s):  
Magnetic Field ◽  
Field Gradient ◽  
Magnetic Field Gradient ◽  
Inertial Range ◽  
Space Plasmas ◽  
Gradient Tensor ◽  
The Magnetic Field

Kalman Filter Processing Applications for Motion Noise

2014 ◽  
Vol 644-650 ◽  
pp. 3964-3967
Author(s):  
Xing Dong Zhang ◽  
Xiao Hong Meng ◽  
Liang Hui Guo
Keyword(s):  
Magnetic Field ◽  
Kalman Filter ◽  
Field Gradient ◽  
Magnetic Field Gradient ◽  
Complex Motion ◽  
Gradient Tensor ◽  
Magnetic Gradient ◽  
Signal Component ◽  
Filtering Effect ◽  
Tensor Data

In geophysics exploration, using gradient tensor instead of the full magnetic field gradient has many advantages, which magnetic gradient tensor data to better describe small anomalies. However, the measurement of magnetic gradiometer contains a very complex motion noise, separating the motion noise from the signal component is a large challenge. In this paper, we show the expression for the magnetic gradient tensor, and then through model tests proved the Kalman filter good filtering effect.

Spectroscopic imaging of human disease

1996 ◽  
Vol 54 ◽  
pp. 884-885
Author(s):  
D.J. Meyerhoff
Keyword(s):  
Magnetic Field ◽  
Magnetic Resonance ◽  
Field Gradient ◽  
Human Disease ◽  
Morphological Changes ◽  
Magnetic Field Gradient ◽  
Spectroscopic Imaging ◽  
Resonance Spectroscopy ◽  
Tissue Water

Magnetic Resonance Imaging (MRI) observes tissue water in the presence of a magnetic field gradient to study morphological changes such as tissue volume loss and signal hyperintensities in human disease. These changes are mostly non-specific and do not appear to be correlated with the range of severity of a certain disease. In contrast, Magnetic Resonance Spectroscopy (MRS), which measures many different chemicals and tissue metabolites in the millimolar concentration range in the absence of a magnetic field gradient, has been shown to reveal characteristic metabolite patterns which are often correlated with the severity of a disease. In-vivo MRS studies are performed on widely available MRI scanners without any “sample preparation” or invasive procedures and are therefore widely used in clinical research. Hydrogen (H) MRS and MR Spectroscopic Imaging (MRSI, conceptionally a combination of MRI and MRS) measure N-acetylaspartate (a putative marker of neurons), creatine-containing metabolites (involved in energy processes in the cell), choline-containing metabolites (involved in membrane metabolism and, possibly, inflammatory processes),

scholarly journals Magnetic hybrid materials interact with biological matrices

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Christine Gräfe ◽  
Elena K. Müller ◽  
Lennart Gresing ◽  
Andreas Weidner ◽  
Patricia Radon ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Field Gradient ◽  
Hybrid Materials ◽  
Biomedical Application ◽  
Magnetic Field Gradient ◽  
Apical Cell ◽  
Cell Type ◽  
Cell Layers ◽  
Barrier Model

Abstract Magnetic hybrid materials are a promising group of substances. Their interaction with matrices is challenging with regard to the underlying physical and chemical mechanisms. But thinking matrices as biological membranes or even structured cell layers they become interesting with regard to potential biomedical applications. Therefore, we established in vitro blood-organ barrier models to study the interaction and processing of superparamagnetic iron oxide nanoparticles (SPIONs) with these cellular structures in the presence of a magnetic field gradient. A one-cell-type–based blood-brain barrier model was used to investigate the attachment and uptake mechanisms of differentially charged magnetic hybrid materials. Inhibition of clathrin-dependent endocytosis and F-actin depolymerization led to a dramatic reduction of cellular uptake. Furthermore, the subsequent transportation of SPIONs through the barrier and the ability to detect these particles was of interest. Negatively charged SPIONs could be detected behind the barrier as well as in a reporter cell line. These observations could be confirmed with a two-cell-type–based blood-placenta barrier model. While positively charged SPIONs heavily interact with the apical cell layer, neutrally charged SPIONs showed a retarded interaction behavior. Behind the blood-placenta barrier, negatively charged SPIONs could be clearly detected. Finally, the transfer of the in vitro blood-placenta model in a microfluidic biochip allows the integration of shear stress into the system. Even without particle accumulation in a magnetic field gradient, the negatively charged SPIONs were detectable behind the barrier. In conclusion, in vitro blood-organ barrier models allow the broad investigation of magnetic hybrid materials with regard to biocompatibility, cell interaction, and transfer through cell layers on their way to biomedical application.

Two-dimensional EPR imaging with the rapid scan and rotated magnetic field gradient

2014 ◽  
Vol 248 ◽  
pp. 126-130 ◽  
Author(s):  
T. Czechowski ◽  
W. Chlewicki ◽  
M. Baranowski ◽  
K. Jurga ◽  
P. Szczepanik ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Field Gradient ◽  
Magnetic Field Gradient ◽  
Two Dimensional ◽  
Rapid Scan
Sign in / Sign up

Export Citation Format

Share Document